There are lots of flights to Hartford from YYZ so see if there is one after yours that has space, just in case. If you arrive in Terminal 3 you'll collect your luggage, clear customs and then take the train to Terminal 1. The connection is quick. But then you have to pre-clear US immigration. You could easily and typically do all of it in 45 minutes - it depends on how long the unloading of luggage takes and how long the two customs and one security lines are. I've seen days when it can all go through in 30 minutes. If you did this in the same terminal, they skip the entry to Canada business and go right to the US pre-clearance.